The present invention relates to chlorobromodicarboxylic acids resulting from the condensation of 2,3-dibromobut-2-ene-1,4-diol or 2,3-dibromobutane-1,4-diol with hexachloroendomethylenetetrahydrophthalic acid, which is commonly referred to as chlorendic acid. It also relates to processes for the manufacture of these products and their use as reactive or unreactive additives for fireproofing synthetic materials.
It is known, from French Pat. Nos. 1,502,049 and 1,502,050, filed Oct. 5th 1966 in the name of PRODUITS CHIMIQUES PECHINEY-SAINT-GOBAIN, to manufacture fireproof synthetic materials, such as crosslinked polyesters, or polyurethanes, starting from products resulting from the polycondensation of mixtures of polycarboxylic acids, which can be polysubstituted by halogen, with 2,3-dibromobut-2-ene-1,4-diol or 2,3-dibromobutane-1,4-diol, which is optionally mixed with another polyol. The diols and polycarboxylic acids are used in proportions such that the resulting polycondensate possesses an excess of alcohol groups, relative to the carboxyl groups. The polycondensates thus obtained have a serious disadvantage. In fact, they consist not of a single product with a well-defined formula, but of a mixture of products in which the composition and the nature of the constituents can vary as a function of the operating conditions used, and especially as a function of the excess of diol, and are very difficult to reproduce. Thus, these mixtures of polycondensates cannot be used in practice as fireproofing agents.